#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <assert.h>
char* my_strcat(const char* str1, const char* str2)
{
	const char* start = str1;
	char* s1 = str1;
	char* s2 = str2;
	while (*s1 != '\0') {
		s1++;
	}
	while (*s1++ = *s2++) {
		;
	}
	return start;
}
int main()
{
	char str1[20] = "abcd";
	char str2[20] = "efg";
	char* ret = my_strcat(str1, str2);
	printf("%s\n", ret);
	return 0;
}